It is frequently the case that a communications subscriber has access to a communications network through more than one access medium. For example, a single residence may have the capability to connect to the Internet through a residential digital subscriber line (DSL) connection and a high-speed cable connection. Further, most DSL and cable users have dial-up network access available as well. Frequently, more than one telephone line in a residence may be used for dial-up access to the Internet.
No network access medium is perfectly reliable. Network connections may degrade or fail for numerous reasons. For example, catastrophic physical problem such as a cable cut may cause a network connection to drop abruptly or suddenly degrade as traffic is rerouted. Network-related problems such as high network traffic volume may cause a network connection to gradually degrade or to fail intermittently.
A failure in a network is not detected by a subscriber until the performance of his or her connection degrades. At that point, the subscriber has several options. The subscriber can tolerate the slowed connection or discontinue the activity altogether. If the subscriber has an alternative connection available, he or she may manually terminate the current connection to the network (if not already terminated) and manually reconnect through the alternate medium. If the application requires a login sequence, then that must be redone. If the connected application is streaming data such as audio or video, then that stream is interrupted for the time taken to change over to the new network access medium.
From a subscriber's point of view, it is difficult to determine whether service degradation is, in fact, due to a failure in an access medium, or is due to other network problems further upstream. For example, in a case where service degradation is due to problems at the application server itself, a subscriber may change from one access medium to an alternative access medium without experiencing any resulting improvement in service quality.
Systems have been proposed to deal with fail-overs in other applications. U.S. Pat. No. 6,389,555 to Purcell et al. discloses a system for handling a link failure within a computer system with peripherals. Upon detection of a failure across a first link, the system engages fail-over mechanisms to re-establish communications over a second link.
U.S. Pat. No. 6,714,534 to Gerszberg et al. proposes a telephone network architecture that bypasses the local exchange carrier. Fail-over lifeline service is provided using cable, twisted pair or wireless solutions. An automatic change-over mechanism is not described.
U.S. Pat. No. 6,373,852 to Foladare et al. discloses an apparatus and method for linking multiple baseband telephone lines to provide broadband communication. For example, the invention allows an individual to use multiple plain old telephone service (POTS) lines in combination to emulate the capability of a broadband line.
There is presently a need for a method and system that can detect and possibly predict a connection failure in a medium providing a wide area network connection. The system should be capable of automatically changing from the failed or failing medium to an alternative, intact medium, with a minimum of disruption to the network connection services.